In general, mobile station (MS) performs a process of selecting a Public Land Mobile Network (PLMN) in order to receive mobile communication services. When MS is turned on, it searches for surrounding PLMNs, selects one of the PLMNs which has the highest priority of order and performs the location registration.
When users register a mobile communication service provider's Identifier (ID) to use roaming services abroad, their MSs may be connected to User PLMN of the service provider. When customers open their accounts with a communication service provider or request an internal roaming service, the service provider creates Foreign PLMN (FPLMN) and provides it to them. When specific codes were not set to MS, the Mobile Entity (ME) may connect to automatically searched provider's networks.
According to the Specification 23.122, when a user manually selects a PLMN, the MS enters a manual PLMN selection mode. While a MS is in a manual PLMN selection mode, the MS is not allowed to register to a different PLMN by itself. Specification, 23.122 section 4.4.3.1.2., is described as follows.
Once an MS has registered on a PLMN selected by the user (manual mode), the MS shall not automatically register on a different PLMN, unless:
i) a new PLMN is declared as an equivalent PLMN by the registered PLMN (RPLMN); or
ii) the user selects automatic mode.
Once a PLMN is selected in a manual PLMN selection mode, the MS does not register on a new PLMN except for the cases described above. Therefore, new systems are required to resolve the problems.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.